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<html lang="en">
<head>
    <meta charset="UTF-8">
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    <title>Document</title>
</head>
<body>
    <button id="btn">dianji</button>

    <script>
        Object.prototype.say = function(){
            console.log('hello')
        }
        document.getElementById('btn').onclick = function(event){
         say()
          say()
        }
    </script>
</body>
</html>